Process for plating of stripes on longitudinal electrically conductive material

ABSTRACT

A process for plating a flexible electrically conductive material such as metallic tape with a thin stripe of metal by passing the moving tape around a groove in the periphery of a disc which is rotated at the same speed in the direction of travel of the tape. Plating solution is supplied to the peripheral groove of the disc to contact the underside of the tape therein, the solution being confined in a narrow channel in the groove so as to plate only that area of the tape immediately above the channel.

United States Patent Thomas Earl Gannoe Warren, Pa.

June 10, 1970 Dec. 21, 1971 Sylvania Electric Products Inc.

Original application Nov. 28, 1967, Ser. No. 686,185, now Patent No. 3,539,490. Divided and this application June 10, 197 0, Ser. No. 45,070 V Inventor Appl. No. Filed Patented Assignee PROCESS FOR PLATING OF STRIPES ON LONGITUDINAL ELECTRICALLY CONDUCTIVE MATERIAL [56] References Cited UNITED STATES PATENTS 2,174,071 9/1939 Grupe 204/28 2,591,042 4/1952 Berman et al.. 204/206 3,008,892 1 H1961 Owen- I 204/207 3,374,159 3/1968 Poole 204/207 FOREIGN PATENTS 176,064 3/1922 Great Britain Primary Examiner-Howard S, Williams Assistant Examiner-T. Tufariello Attorneys-Norman J OMalley, Donald R. Castle and Frederick H. Rinn 4 Claims 9 Drawing Figs ABSTRACT: A process for plating a flexible electrically con- U.S.Cl .L 204/28, ductive material such as metallic tape with a thin stripe of 204/l5,204/207 metal by passing the moving tape around a groove in the Int. Cl C231) 5/48, periphery of a disc which is rotated at the same speed in the C23b 5/58, BOlk 3/00 direction of travel of the tape. Plating solution is supplied to Field of Search 204/206, the peripheral groove of the disc to contact the underside of 28, 212, 15,207, 224 the tape therein, the solution being confined in a narrow channel in the groove so as to plate only that area of the tape immediately above the channel.

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ATTORNEY PATENTED DELZI l9?! SHEET U 0F 4 H N: :w Wm l l l l l I ll L INVENTOR. THOMAS E. GANNOE @MM QM ATTORNEY PROCESS FOR PLATING OF STRIPES N LONGlITlUDWAlL ELECTRICALLY CONDUCTIVIE MATERIAL CROSS REFERENCE TO RELATED APPLICATION This application is a divisional application of S. N. 686,195, filed Nov. 28, 1967 and now U.S. Pat. No. 3,539,490, which is assigned to the assignee of the present invention.

BACKGROUND OF THE INVENTION The invention relates to the plating of metals and more particularly to a process for applying a metallic plating to a discrete portion of a flexible electrically conductive material, such as a metallic tape.

Previously, metallic stripes could be applied on a tape of electrically conductive material by several known techniques with varying degrees of success. Conventional procedures such as brush plating and overall plating techniques usually provided lesser thicknesses of plating than was desired in the functional areas. Furthermore, the overall plating process wasted plating material in unnecessary and unwanted areas, such deposition required subsequent steps to remove undesired plating. By the brush plating technique, it was difficult to hold close tolerances in specific areas. The application of metallic stripes by inlay, overlay or continuous strip welding techniques usually required strip material of a' greater thickness than desired and needed for the finished product.

OBJECTS AND SUMMARY OF THE INVENTION It is an object of the invention to reduce the aforementioned difficulties and to provide an improved process for plating a discrete stripe of metal on a flexible electrically conductive material.

Another object is to provide a process for disposing a metallic stripe having uniformity of width and thickness on a metal tape of dissimilar material.

A further object is to provide a rapid and expeditious process for applying a metallic stripe of heavy uniform plating to a moving metal tape.

The foregoing objects are achieved in one aspect of the invention by the provision of a process for applying a stripe of metal to a flexible electrically conductive material such as a metallic tape. The plating is applied to the moving tape in a rapid and expeditious manner by moving the container for the plating solution along with the tape; the container being fed with fresh plating solution at locations spaced from each other in the direction of travel of the tape.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. la and lb together comprise a schematic layout of an apparatus for plating a tape;

FIG. 2 is an elevational view; partly in section, of a plating disc and adjacent parts;

FIG. 3 is a section taken along the line 3-3 of FIG. 2;

FIG. 4 is a view of parts, partly in section as viewed from the plane of line 4-4 in FIG. 2;

FIG. 5 is an enlarged sectional view of the upper portion of FIG. 3;

FIG. 6 is an elevational view, partly in section, of a modified form of plating disc and adjacent parts;

FIG. 7 is a view of a fragmentary portion of a tape having a stripe thereon applied in accordance with this invention; and

FIG. 8 is a diagrammatic view of a tape drive and takeup mechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENT For a better understanding of the present invention, together with other and further objects, advantages and capabilities thereof, reference is made to the following specification and appended claims in connection with the aforedescribed drawings.

With reference to the drawings, there is shown in FIGS. la and lb a bench indicated generally as 10, having support arms 12 for supporting in conventional fashion a supply reel M of a flexible longitudinal electrically conductive material such as metallic tape 16. The tape may be of any metal and of any width, length and thickness desired. As an example, only, the tape may be of beryllium copper, 0.009 inches thick, seveneighths of an inch wide and unlimited length. On this tape there is to be plated, a metal, which may be, for example, a 24- carat gold stripe, 0.0008 inch in thickness and one-sixteenth of an inch'in width.

The tape is pulled through cooperating rollers 20 and 24 accommodated on roll stand it At least one of the rollers of the roll stand, as lower roller 20, is of metal, connected by any suitable means to the negative pole of a DC source of supply, as through a conductor 22 and a metal bearing supporting the roller. The other roller, as upper roller 24, may be of rubber, such rubber being springpressed onto the tape to effect good electrical contact of the tape with the lower roll. The tape is initially passed through a tank 26 on the bench, said tank containing a caustic metalcleaning solution, thence past a pair of squeeze rolls 28 into a caustic rinse tank 30, past another pair of squeeze rolls 32 and into a caustic neutralizing and acid coating tank 34 containing, for example, a 50 percent hydrochloric acid solution. After passing through the tank 34, through squeeze rolls 36, and through hydrochloric acid rinse tank 30, the tape passes through a pair of rollers 410 positioned on a roll stand similar to roll stand 18. At least one of the rollers is metal and has a cathode lead 41 connected thereto. The tape is then pulled through a plating tank 42 containing a solution of nickel chloride, the electrolytic solution in the tank contacting an anode in the tank as is conventional in the art. The purpose of the nickel chloride plating is to deposit a thin film or strike of nickel on the tape substrate, so that the metal, such as gold, subsequently plated on the tape will have good adherence thereto.

After being pulled through the nickel plating tank, the tape passes through the squeeze rollers M, nickel chloride rinse tank 46, and contactor rollers 48 which are similar to those positioned on stand 18, with a cathode lead 48 being connected to at least one of the rollers. The purpose of using the contactor rolls in the contactor roll stands is to ensure that the tape is electrically connected to the cathode of the source of electrical supply. The various tanks described herein may be heated if desired. The cleaning of the metal is by means known in the art and need not further be described. The application of a nickel strike to the tape while enhancing the quality of the final product is not absolutely necessary and may, if desired, be omitted.

After the tape has been drawn through the nickel chloride rinse tank it is preferably initially given a thin strike in stripe form of the metal which is to be subsequently applied in heavier stripe form on the tape. As shown in the drawings, the tape is drawn through a gold stripe electrolytic tank 50, which has within it a very narrow sponge longitudinally oriented in the direction of movement of the tape and of the width of the stripe desired; the sponge being positioned to rub against the under face of the tape. The sponge is partially immersed in tank 50 containing an acidulated solution of gold salts, the solution being in electrical connection with an anode within the tank which is connected to the DC supply so that, through the saturated sponge, an electrolytic plating action is consummated on the moving tape.

The tape, after passing over a direction changing roll 51, is next passed around and in tight engagement with a peripheral portion of an insulating disc 52 mounted on a horizontal axle. As the tape is pulled in an advancing manner, it effects rotation of the disc. It is while the tape is on this disc that the metallic stripe of predetermined thickness is applied. The thickness of the plating depends on the velocity of movement of the tape (and therefore the rotational velocity of the wheel), the concentration and rate of continuous replenishment of the plating electrolyte, the effective depth of the electrolyte, temperature, electrical conditions etc., all of which are empirically determined for the results desired.

In the form of invention illustrated in FIG. 2, the tape is passed beneath and around a metallic guide roller 54 near the bottom of the disc 52 and up and around the roller and around the disc for substantially the greater portion of its circumference. The tape rides tautly in a groove 56, FIGS. 3 and formed in the circumference of the disc. The construction of this disc will be described in greater detail subsequently.

After passing about the disc 52, the tape is trained around a second metallic guide roller 57 and over a direction controlling roller 58 into and through a deplating or precious metal recovery tank 59 having a cathode connected to an independent source of DC supply where any small amount of metal which may have been deposited on the tape outside of the stripe area, by reason of seepage of electrolyte or otherwise, is removed. However, because the undesired deposit is very thin, the amount of deplating action is very little and affects the stripe to an exceedingly limited degree so that only a very small percentage of the thickness of the stripe itself is removed.

After passing through the metal recovery tank, in this case the gold recovery tank, the strip is pulled through metal squeeze rollers 60 connected to the positive pole of the independent DC supply, FIG. lb, a final rinse tank 61, squeeze roller 62 and in the space between an elongated spaced parallel pair of heaters 64, and a guide roller 66. The tape in this form of invention is driven by a pair of tape drive rolls 68, as shown in FIG. 8, which are in turn driven by an appropriate motor 70. The tape is then wound on a takeup reel 72, the reel being driven through a slip clutch 74 from the motor means 70. Obviously, the tape may be driven synchronously with the rotation of disc 52 by other suitable means not shown.

Adverting to FIGS. 2 and 3, it will be noted that the bench supports a vertical inverted U-shaped frame 78 of angle irons supported by struts 80, one on each side of the frame, the frame being reinforced by a horizontal angle iron 82. The frame members are further reinforced through being spanned by a metallic web mounting plate 84 which plate also serves the purposes of supporting the disc 52 and the two guide rolls 54 and 57. Also supported on the plate is a conductive stud 86 to which is connected the cable 88 leading to the positive pole of the DC source. The stud passes through an insulating bushing 90, see FIG. 5, and has a spacer 92 thereabout, the stud being provided with spring fingers 94, the spring fingers bearing against a circular conducting ring 96 mounted on the back of the disc 52.

Also fixed to the web 84, see FIG. 4, as by stand-off bushings 98 is a conductive bar 100 connected by a lead 102 to the negative pole of the DC source. This bar is connected by pigtails 104 to conductive brushes 106, which are spring pressed in appropriate holders 108 toward the strip as it passes over the guide rollers 54 and 57. The guide rolls 54 and 57 are rotatably mounted on stub shafts 110 forming part of blocks 112, see FIG. 3, which are fastened to the web plate by bolts 114 and each being held on its respective shaft by a washer 116 and bolt 118. A reinforcing plate 120 may be applied to the web plate 84 at the lower portion thereof to aid in supporting the guide rolls and to serve as a splash plate for electrolyte flowing from the plating disc.

The disc, see particularly FIGS. 3 and 4, is a two part member comprising a rear portion 122 and a front portion 124, the two portions when bolted together, as by bolts 126, or when cemented together presenting the peripheral groove 56 in which the tape 16 rides. Near the periphery of each of the two members in a liquid flow undercut portion which when the members are united, produce an elliptical channel or passageway 128 and a throat 130 with parallel sidewalls connecting the elliptical passageway with the groove 56 so that electrolyte flowing in the passageway also flows via the throat against the undersurface of a narrow longitudinal area of the tape. In order to conduct DC positive potential to the electrolyte flowing in the passageway and throat, a conducting ring 132 is embedded in the forward face of rearward member 122, whose outer peripheral face is part of the wall of the passageway or channel 128 in the member 122; this ring being connected at equally spaced intervals via conducting screws 134 with the circular conducting ring 96 on the rear face of the disc.

The rear face of the front member 124 of the disc is provided with a plurality of conducting grooves 136 arranged like spokes in a wheel, these grooves communicate at the peripheral portion of the disc with the elliptical passageway and near the center of the disc with a pipe 137 leading to a source of electrolyte.

The disc at its center has a bearing 138 of wear resistant material afiixed to the disc which bearing and disc are rotatably mounted on a stub shaft 139 held to the web plate by screws 140. Suitable O rings 141 are provided to prevent fluid leakage between the shaft and bearing. A circular retaining plate 142 for the disc and bearing overlaps the disc bearing and stub shaft and is fastened to the stub shaft by screws 144. The rear face of the disc bears against a shoulder 146 on the stub shaft. The stub shaft has an upper portion thereof channeled to form a manifold 148, see FIGS. 2 and 3, serially communicating with the grooves 136 as the disc is rotated by reason of the frictional contact with the moving tape, several of the grooves being open to the manifold at any interval of time. The pipe 137 conducts electrolyte to the manifold. This electrolyte may be fed to the pipe either by gravity from a reservoir adjacent the disc or by a force pump. If by a gravity supply, it is preferable that the top level of the electrolyte in the reservoir be just above the level of the electrolyte in the top of the throat so that very little fluid pressure will exist at the contact area of tape and disc to minimize forcing of fluid out of the throat and leakage thereof along the undersurfaces of the tape, should the tape be warped. If flow of electrolyte is effected by a force pump, the pressure should be low.

The electrolyte by virtue of its pressure, whether by static pressure or force pump, will flow up the grooves 136 which are in communication with manifold 148 and against the undersurface of the tape at the area exposed through the throat. The liquid will then flow by gravity down in the passageway and throat on both sides of the disc and in contact with the tape and be discharged at the bottom of the disc.

Thus contact of the electrolyte with the tape will be made for a comparatively long time so that a heavy stripe plating of the tape, as the stripe 151, FIG. 7, is effected, the plating being effective simultaneously throughout the length of tape in contact with the throat.

An electrolyte delivery mouth 152 is located between the two guide rollers 54 and 57 and resilient portions 153 thereof are in liquid stripping contact with the plated face of the tape to guide the effluent from the disc to an electrolyte receiving tank 154 below the mouth. A front splash plate 156 is mounted on the tank in any convenient fashion, as by fork arms 157, to prevent electrolyte splash. The tank has mechanism (not shown) associated with it to normalize the strength of the metal salts in the solution, and the liquid in this tank is either pumped into the inlet pipe 137 or pumped into the constant liquid level reservoir from which the fluid is fed to the pipe 137.

In a modified form of invention shown in FIG. 6, the guide rolls 54 and 57 are replaced by rolls 160 and 162 and the tape leaving the gold stripe tank 50 passes between a pair of direction changing rolls 51 and 164 to the roll 160. When the tape leaves the roll 162 it is guided by the rolls 58 and 166 to the gold recovery tank 59. The stub shaft 168 in this form of the invention instead of having a single manifold portion, as portion 148 in the previously described form of invention, has two vertically opposed manifolds 170 and 172, the manifold 170 communicating with a pipe 174 leading to a constant level supply reservoir 176 supplied from the electrolyte normalizing tank 154 by suitable pump 178, piping 180 and a conventional float level control valve 182. The reservoir in this case is preferably located with the top surface of the liquid therein at the level of the bottom of the peripheral groove 56 in the disc or slightly above the groove.

As in the previous form of invention several conducting grooves 136 communicate simultaneously with manifold 170. Likewise in this form of invention a plurality of grooves communicate with manifold 172, which is evacuated via pipe 186 and suction pump 188; the suction pump discharging into the normalizing tank 154. As a result, plating electrolytic solution is fed from the reservoir 176 to manifold 170, thence via a number of conducting grooves 136 and by gravity flow to the top of the throat in the disc, thence downwardly on both sides of the disc in contact with the underside of a portion of the tape toward the lowermost ones of the grooves 136, from which grooves the electrolyte is by suction transferred to manifold 172 and to the normalizing tank 154. With this form of the invention, leakage by reason of warped tape material is reduced to a minimum since no pressure system is involved in effecting the contact of the electrolyte with the tape.

Thus, there is provided an improved process for plating a discrete stripe of metal on a flexible electrically conductive material. By this process a metal stripe having uniformity of width and thickness is expeditiously and economically disposed on a moving tape material in an efficiently controlled and practical manufacturing manner.

While there have been shown and described what are at present considered the preferred embodiments of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the scope of the invention as defined by the appended claims.

In the claims:

1. A processfor electrolytically plating a moving longitudinal electrically conductive flexible material with a stripe of metal comprising the steps of:

moving said conductive material and a body providing a plating solution flow path together in the direction of movement of said material, said conductive material being moved through an arcuate path in a vertical plane;

supplying the flow path in said moving body with a flowing plating solution in a manner to contact a narrow portion of said conductive material, said solution being fed to an area of said conductive material at a high area thereof, said solution then flowing downwardly toward the low points of said arc while in contact with said conductive material in both sides of said arc; and

supplying said conductive material and said solution with electric current to effect deposition of plating material from said solution onto said conductive material.

2 K process as set forth in claim 1 wherein said conductive material is of beryllium and wherein said conductive material is precoated with nickel prior to the application of said metal stripe to enhance the adherence of said strip thereon.

3. A process as set forth in claim 2 wherein said metal stripe is gold, and wherein said conductive material is precoated with a strike of nickel prior to the application of said metal stripe.

4. A process as set forth in claim 1 wherein a preliminary stripe of said metal is initially applied to said conductive material in substantially the same area subsequently striped by passing said material over a sponge saturated with plating solution, the sponge being narrow and elongated in the direction of travel of said material. 

2. A process as set forth in claim 1 wherein said conductive material is precoated with nickel prior to the application of said metal stripe to enhance the adherence of said strip thereon.
 2. A process as set forth in claim 1 wherein said conductive material is of beryllium and wherein said conductive material is precoated with nickel prior to the application of said metal stripe to enhance the adherence of said strip thereon.
 3. A process as set forth in claim 2 wherein said metal stripe is gold, and wherein said conductive material is precoated with a strike of nickel prior to the application of said metal stripe.
 4. A process as set forth in claim 1 wherein a preliminary stripe of said metal is initially applied to said conductive material in substantially the same area subsequently striped by passing said material over a sponge saturated with plating solution, the sponge being narrow and elongated in the direction of travel of said material. 